The Earth continuously emits 100 million gigawatts of infrared heat into outer space. That’s enough to power all of humanity many thousands of times over. Capturing even a fraction of that would mean an end to our energy woes. Harvard University researchers are now proposing a way to harvest this untapped source of renewable energy.

They have come up with two designs for a device they call an “emissive energy harvester” that would convert IR radiation into usable power. Today's technology isn't sufficient for an efficient, affordable harvester, the researchers say. But they've laid out a few different paths towards such devices in the journal Proceedings of the National Academy of Sciences.

A Stanford engineering team has built a radio the size of an ant, a device so energy efficient that it gathers all the power it needs from the same electromagnetic waves that carry signals to its receiving antenna – no batteries required.

Designed to compute, execute and relay commands, this tiny wireless chip costs pennies to fabricate – making it cheap enough to become the missing link between the Internet as we know it and the linked-together smart gadgets envisioned in the "Internet of Things."

"The next exponential growth in connectivity will be connecting objects together and giving us remote control through the web," said Amin Arbabian, an assistant professor of electrical engineering who recently demonstrated this ant-sized radio chip at the VLSI Technology and Circuits Symposium in Hawaii.

Much of the infrastructure needed to enable us to control sensors and devices remotely already exists: We have the Internet to carry commands around the globe, and computers and smartphones to issue the commands. What's missing is a wireless controller cheap enough to so that it can be installed on any gadget anywhere.

"How do you put a bi-directional wireless control system on every lightbulb?" Arbabian said. "By putting all the essential elements of a radio on a single chip that costs pennies to make."